Modem life's demands bring about changes in the space configuration of buildings. New needs arise that the existing installations in buildings cannot meet and therefore lead to the use of accessory installations exposed on the surface. The existing systems with self-affixing means attempting to solve the above mentioned problem may be classified into two groups: a) surface conductors and b) cable carry ducts.
When considered as a whole, the systems above, obviously contemplate many of the problems posed by this kind of installation. However, when individually analyzed, they show inherent design limitations that leave a great deal of the problems unsolved.
For example, some systems whose conductors are wires, are flexible enough to suit various surface types, yet they cannot be easily spliced, which hampers the use of fittings. Examples: Cabral, U.S. Pat. No. 2,831,049; Stern U.S. Pat. No. 3,253,085; Hirtle, U.S. Pat. No. 2,701,819.
Other systems using rigid tubes as the electrical current conductor element may be relatively easily assembled by using connecting pins; however, the tubes' own rigidity prevents them from adapting to irregularly shaped surfaces. Such is the case of O'Brien, U.S. Pat. No. 2,413,032, who presents a continuous metallic tube requiring certain rigidity to perform its function; that rigidity becomes a problem in other senses. For example, contact reliability is little, since there is little tolerance allowed to achieve good adjustment between the connecting pin and the rigid tube. Therefore, a slight difference may impair contact between elements. Rigidity is a problem too in, cable carrying ducts, Santucci's, U.S. Pat. No. 4,602,124 which are extremely rigid on account of their double "U-shaped" structure (base and cover) which makes it impossible to adjust a channel with a section of that shape to a curved surface, for example. That same structure composed of double sidewalls made up of U-shaped channel and U-shaped channel cover sidewalls) is ugly and takes up space. In addition, it features superfluous insulating material in excess of the insulation provided in the cables that are carried.
The rigidity of systems with both rigid tubular conductors (O'Brien) and cable-carrying ducts (Santucci) complete the manufacturer to provide short lengths, which increases the number of cuts and splices, thus deteriorating the aesthetic aspect of the installation. Cable-carrying ducts are extremely useful for industrial applications, where it is necessary to protect and systematize installation of conductors, paying little attention to the aesthetic aspect. However, they do not solve the aesthetic/functional problem of urban uses, where the decorative aspect is important.
The above mentioned, already existing systems, do not provide a solution to the problem posed by the need to penetrate a wall or partition wall in order to extend installation from one room into another. In contrast, the system proposed herein makes it possible to extend installations from one partition's side into the other by combining conductors located concentrically and in juxtaposition through the use of an interconnecting plug.